rtnl: limit IFLA_NUM_TX_QUEUES and IFLA_NUM_RX_QUEUES to 4096

We have an impressive number of syzkaller bugs that are linked to the fact that syzbot was able to create a networking device with millions of TX (or RX) queues. Let's limit the number of RX/TX queues to 4096, this really should cover all known cases. A separate patch will add various cond_resched() in the loops handling sysfs entries at device creation and dismantle. Tested: lpaa6:~# ip link add gre-4097 numtxqueues 4097 numrxqueues 4097 type ip6gretap RTNETLINK answers: Invalid argument lpaa6:~# time ip link add gre-4096 numtxqueues 4096 numrxqueues 4096 type ip6gretap real 0m0.180s user 0m0.000s sys 0m0.107s Fixes: 76ff5cc ("rtnl: allow to specify number of rx and tx queues on device creation") Signed-off-by: Eric Dumazet <[email protected]> Reported-by: syzbot <[email protected]> Signed-off-by: David S. Miller <[email protected]>
ambv · Oct 2, 2018 · 0e1d6ec · 0e1d6ec
1 parent 0f3b914
commit 0e1d6ec
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
@@ -2835,6 +2835,12 @@ struct net_device *rtnl_create_link(struct net *net,
 	else if (ops->get_num_rx_queues)
 		num_rx_queues = ops->get_num_rx_queues();
 
+	if (num_tx_queues < 1 || num_tx_queues > 4096)
+		return ERR_PTR(-EINVAL);
+
+	if (num_rx_queues < 1 || num_rx_queues > 4096)
+		return ERR_PTR(-EINVAL);
+
 	dev = alloc_netdev_mqs(ops->priv_size, ifname, name_assign_type,
 			       ops->setup, num_tx_queues, num_rx_queues);
 	if (!dev)